Limit Member Directory search to display_name only

my_pmpro_member_sql_search_where.php

<?php
/**
 * Limit Member Directory search to display_name only.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_member_sql_search_where_display_name_only( $sql_search_where, $s ) {

	$sql_search_where = "
		AND (
			u.display_name LIKE '%" . esc_sql( $s ) . "%'
		)
	";

	return $sql_search_where;
}
add_filter( 'pmpro_member_directory_sql_search_where', 'my_pmpro_member_sql_search_where_display_name_only', 10, 2 );